1. A belt tensioner for a motor vehicle engine, comprising:
a pivot shaft configured to be mounted stationary relative to the motor vehicle engine;
a pivot arm pivotally mounted on said pivot shaft;
a pulley rotationally supported on said pivot arm;
a spring that biases said pivot arm in a belt take-up direction; and
a backstop device operably engaging said pivot arm to provide a predetermined, limited amount of rotational play therebetween and to prevent rotational movement of said pivot arm from a minimum belt take-up position in a direction opposite said belt take-up direction, said backstop device comprising a one-way clutch member and a frictional brake member, said frictional brake member being a frictional clamp member relatively fixed to said pivot shaft by means of frictional engagement therewith, said frictional engagement being overcome manually during installation to rotationally position said backstop device to engage the pivot arm when in the minimum belt take-up position, said one-way clutch member including a pair of axially aligned rotational members disposed around said pivot shaft, one of said rotational members engaging said pivot arm and the other of said rotational members is a clamp holder which engages said frictional clamp member, at least one of said rotational members having a cylindrical surface, wherein said one-way clutch member further includes a clutch spring, one end of said clutch spring overlapping said cylindrical section of said at least one of said rotational members and the opposite end of said clutch spring being attached to the other of said rotational members, said clutch spring thereby permitting said rotational members to rotate in one direction relative to each other to permit said pivot arm to pivot substantially freely in said belt take-up direction but substantially preventing said rotational members from rotating in an opposite direction relative to each other to resist pivoting of said pivot arm in said direction opposite to said belt take-up direction.
2. The tensioner of claim 1, wherein the level of said frictional engagement between said frictional brake member and said pivot shaft is large enough to stop pivoting of said pivot arm in said direction opposite to said belt take-up direction when said pivot arm is subjected to belt load-induced torque under normal engine operating conditions and small enough to allow said pivot arm to be pivoted manually during installation in said direction opposite to said belt take-up direction.
3. The tensioner of claim 2, wherein said frictional brake member is constructed to open at least partially when said pivot arm is pivoted manually during installation in said direction opposite to said belt take-up direction.
4. The tensioner of claim 1, wherein said play is approximately the same as a rotational degree of pivot arm movement that is attributable to thermal expansion of the engine.
5. The tensioner of claim 1, wherein said play is approximately the same as the combination of a rotational degree of pivot arm movement that is attributable to thermal expansion of the engine and a rotational degree of pivot arm movement that is attributable to dynamic, engine-induced vibration of said pivot arm.
6. The tensioner of claim 1, wherein said clutch spring has a tang by means of which said clutch spring is anchored to said rotational member which engages said pivot arm.
7. The tensioner of claim 1, wherein said pair of rotational members are axially interconnected directly with each other.
8. A belt tensioner for a motor vehicle engine, comprising:
a pivot shaft configured to be mounted stationary relative to the motor vehicle engine;
a pivot arm pivotally mounted on said pivot shaft;
a pulley rotationally supported on said pivot arm;
a spring that biases said pivot arm in a belt take-up direction; and
a backstop device installed about the pivot shaft and operably engaging said pivot arm providing a predetermined, limited amount of rotational play between said pivot arm and said backstop device and preventing rotational movement of said pivot arm from a minimum belt take-up position in a direction opposite said belt take-up direction, said backstop device including a frictional clamp member and a one-way clutch member including a pair of axially aligned, generally cylindrical members disposed around said pivot shaft, one of said generally cylindrical members having an arm-engaging portion engaging said pivot arm and the other of said generally cylindrical members is a clamp holder which supports said frictional clamp member, and wherein said one-way clutch member includes a clutch spring which overlaps said pair of generally cylindrical members and permits said generally cylindrical members to rotate in one direction relative to each other permitting said pivot arm to pivot substantially freely in said belt take-up direction, but substantially prevents said generally cylindrical members from rotating in an opposite direction relative to each other resisting said pivot arm from pivoting in a direction opposite to said belt take-up direction by engagement of said pivot arm by said arm-engaging portion, frictional engagement of said frictional clamp member with said pivot shaft, and interlocking action of said one-way clutch member between said frictional clamp member and said arm-engaging portion.
9. The tensioner of claim 8, wherein the level of said frictional engagement between said frictional clamp member and said pivot shaft is large enough to resist pivoting of said pivot arm in said direction opposite to said belt take-up direction when said pivot arm is subjected to belt load-induced torque under normal engine operating conditions and small enough to allow said pivot arm to be pivoted manually during installation in said direction opposite to said belt take-up direction.
10. The tensioner of claim 8, wherein said clamp holder comprises an upper, clamp sleeve member and a lower, bottom sleeve member and wherein said frictional clamp member is housed between said upper, clamp sleeve member and said lower, bottom sleeve member.
11. The tensioner of claim 8, wherein said clutch spring is connected to said generally cylindrical member which engages said pivot arm.
12. The tensioner of claim 8, wherein said pair of generally cylindrical members are axially interconnected directly with each other.
13. The tensioner of claim 8, wherein an amount of play is provided between said pivot arm and an engagement portion of said generally cylindrical member engaging said pivot arm.
The claims below are in addition to those above.
All refrences to claims which appear below refer to the numbering after this setence.
1. A mobile device for displaying construction-related documents, comprising:
at least one touch-sensitive display surface;
at least one image capture device;
a rugged casing; and
at least one handle.
2. The mobile device of claim 1, wherein the handle is integral to the rugged casing.
3. The mobile device of claim 1, wherein the handle is retractable into the rugged casing.
4. The mobile device of claim 1, wherein the rugged casing is constructed of magnesium alloy.
5. The mobile device of claim 1, further comprising:
a processor;
a storage medium;
an optical drive;
a global positioning sensor;
at least one power source; and
a plurality of external connection ports.
6. The mobile device of claim 1, further comprising shock-, moisture-, dust- and vibration-resistant components.
7. The mobile device of claim 1, further comprising:
a touch-screen interface for viewing, editing and annotating documents.
8. The mobile device of claim 7, wherein the documents are construction-related documents.
9. The mobile device of claim 7, wherein the documents are still or moving images.
10. A method of displaying construction-related documents, comprising:
selecting, via a touch-screen interface, a construction-related document from a list of construction-related documents stored on a mobile device;
displaying the selected construction-related document on the screen of the mobile device;
editing or annotating the construction-related document;
storing an updated version of the construction-related document on the mobile device; and
tracking and maintaining a version history of previous versions of the construction-related document.
11. The method of claim 10, further comprising:
receiving a construction-related document from a remote device; and
storing the construction-related document on the mobile device.
12. The method of claim 11, further comprising:
sending the updated version of the construction-related document to the remote device.
13. The method of claim 10, further comprising:
utilizing a global positioning sensor to display construction-related documents relating to construction sites that are proximate to the location of the mobile device.